1. Field of the Invention
This invention relates to diamond studded drag bits.
More particularly, this invention teaches a means to prevent the diamond insert stud bodies from rotating in their interference fit sockets formed in the face of the bit body while simultaneously providing a conduit means to clean and cool each diamond faced stud as it works in a borehole.
2. Description of the Prior Art
Prior art rock bits that utilize chisel crested tungsten carbide inserts or diamond faced inserts on the cutting face of the bits sometimes have a problem with insert pulling or insert rotation while working in a formation. If these inserts should dislodge themselves from their interference fit sockets, the resultant "junk" in the borehole will soon destroy the rest of the bit. Chisel crested tungsten carbide and diamond studded inserts out of necessity have a specific orientation with respect to the cutting end of the rock bit to effect maximum hole penetration of the rock bit. If either of these inserts should rotate, bit penetration deteriorates markedly. Moreover, if the inserts are loosened due to rotation they are more likely to fall out of the bit, resulting in catastrophic failure of the bit.
U.S. Pat. No. 1,041,568 discloses a diamond drill wherein diamond tipped stud bodies are secured from rotation by notching the bit body. The body is so shaped to accept the rectangularly shaped stud.
Another prior art U.S. Pat. No. 4,073,354, discloses a drag type drill bit wherein the cutter retaining stud body is provided with an indexing means. A flat section in the body registers with a complementary receptacle in the face of the drag bit to prevent rotation of the cutter insert stud.
Both of the above patents however are disadvantaged in that, while the inserts are prevented from rotation, there is no means to cool and clean each insert while it works in the borehole. Consequently, the prior art bits easily "ball up", thus rendering the bits ineffective. Balling is caused by the sticky formation adhering to the cutting face of the bit. This occurs in certain formations where the hydraulic action of the drilling "mud" is inadequate. In addition, the hydraulic passages in the bit may be poorly designed, resulting in inefficient cross-flow of mud across the face of the bit.
The instant invention obviates these disadvantages by providing a means to prevent the diamond studded inserts from rotating while providing a means to cool and clean each insert while the bit penetrates the borehole.